IDENTIFYING MECHANISMS BEHIND POLICY INTERVENTIONS VIA CAUSAL MEDIATION ANALYSIS. (20th May 2015)

• Record Type: Journal Article
• Authors: Keele, Luke; Tingley, Dustin; Yamamoto, Teppei
• Is Part Of: Journal of policy analysis and management. Volume 34:issue 4(2015)
• Page Start: 937
• Page End: 963
• Publication Date: 2015-05-20
• Subjects: causal mechanisms -- noncompliance -- instrumental variables -- direct and indirect effects -- potential outcomes -- sensitivity analysis -- mediation; Policy sciences -- Periodicals; Political planning -- United States -- Periodicals; United States -- Social policy -- Periodicals; 353
• DOI: 10.1002/pam.21853
• Languages: English
• ISSNs: 0276-8739

Abstract

Abstract: Causal analysis in program evaluation has primarily focused on the question about whether or not a program, or package of policies, has an impact on the targeted outcome of interest. However, it is often of scientific and practical importance to also explain why such impacts occur. In this paper, we introduce causal mediation analysis, a statistical framework for analyzing causal mechanisms that has become increasingly popular in social and medical sciences in recent years. The framework enables us to show exactly what assumptions are sufficient for identifying causal mediation effects for the mechanisms of interest, derive a general algorithm for estimating such mechanism‐specific effects, and formulate a sensitivity analysis for the violation of those identification assumptions. We also discuss an extension of the framework to analyze causal mechanisms in the presence of treatment noncompliance, a common problem in randomized evaluation studies. The methods are illustrated via applications to two intervention studies on pre‐school classes and job‐training workshops.